Pit prop



Patented June 17, 1930 E'Noorrl nunnouen, on AsnTon-IN-MAKFIELD, nnennnn fm, my

Application nieu Nyefber v1a-isms, serial TNO'. 318,529; airain ere'atcnritin November i7, 1927;

y .;,Myjinfvention relates totali limprovedfpit prop'for mining. and other-.purposes which lis capable of being adjusted in .length to ysuit the positionmin which: it isftoibefused.

. The object'ofthis inventionristo provide a simple arrangement of adjustable pit prop adapted'to be altered in length to'suit the .position inl which it is to'be used, and which aiordsa means for taking "up exceptional o fthepropmj l l Broadly a pitprop according-to'myinven- -tion' comprises two tubular members slidable one within the other and adapted-'to beheld in selected relative positions by7 a filling mefdium "introduced into one .of the `tubular members, being providedwhereby under eX- cessive pressuregthe filling medium: escapes from the tubular member?l accommodating-it.

, lgstrain's without causing bending or fracture l2o'fAccording to the preferredformo tliis invention my improved pit prop'is formed in two parts each of tubular `:form one ladaptedito telescope into the'vother. :A suitable -oot is secured yto the-end of. one tubular por- .25 tion'and a cap vor headl is secured'to the opposite end of lthe othery tubular 1 portion. The largerI tubular member preferably com- 'prises'the/base or lower portion of the prop whilst? the smaller tubularfmelnber lits vin l1: 30 the upper end thereof. Uponthe lower end fofthe upper member is provided ai collar whichfis-a' good lit/in the lower memben This collar constitutes a piston or abutment which restson material .packetfinto the .35 lowerportionand is provided-with means for releasing-some of the-material'when the pressure onptlie prop :causes the-materialto be compressed beyond la'fpredetermined.eX- tenthl For this purpose' a=lconical opening *140 may be formedin the fpistonor inan interchangeable plate secured'thereto. Suitable means Ai'or adjusting thel size Lof the opening may be2/provided,

Y l Intothe lower and larger tubular portion 'lf-i5 of ymy improvedpitprop isplaced a quantity offs'tone' dust', sand orother suitable material. A suiiicient quantity of'this isfplaced inthe flower Vmember until it supports the upper member at Athe desired heightn- The two portions 'areVA then. held r iniy place: vby

means of a collar placed around the upper .lend of-.thelower kmember andy secured by ysuitable locking pins/This collar projects above the topjo theflower member and valso engages around` the upper member where it, Y

for some ofl the stone or other, dustand its;HK

'sizeandshape fisarranged or adjusted to permit; this to occurvbeforethe loadbecomes sufficient to cause lbending or fracture of the '-.weakest part of theA prop whichisthe upper memben i 1 j ,Y i.

Thebase or foot may comprise a suitable iron: casting ghaving'a recess formed therein for the're'ception of the bottom end of the 'lower tubular portion of the pit prop. This Ymay be securedin positionby one ormore pins passedithrough'holes .therein so kas to engage` partlyin the casting and partly in the tubular member. The cap upon the-upper end of the pit prop may also be formed of a suitable iron or other castinglhaving a.; recessin its underface adapted tofit over the top/of theyuppertubular` portion ofthe prop. A3 suitable vhole maybe provided yin the ycentreloi'ft-hi's casting-if desired. `A suit- {ab'le openingf'may be kprovided in the lower lmemberne'ar its base from which thestone Vor other dust maybe raked out when itis desiredtoreleas'e' a pit prop for removal or in order toatlord av fine adjustment'by' re- 'moving al smallk quantity of thedust'. 1A" k'suitable v`cover mayy be normally secured yover j thsornng- 5 {.inventions maybe clearly funderstood Y.and readily' carried into effect2 9 so i ` ment or piston.

Fig. 4 is a section on the line C-D of Fig. 3.

Fig. 5 is a plan view of a slightly modified form of apertured plate for use with the said piston or abutment.

Fig. 6 is a section on the line E-F of Fig. 5, and

Fig. 7 is a detail sectional elevation View of the lower prop lmember showing a device for extracting the packing material from the prop for reducing the height of the prop. Y

Referring to the drawings the Vpit prop illustrated consists of an upper tubular Vmetal part 1 slidable'in lthe slightly larger diamter interior of a lower tubular metal part v2 which has fitted to it a flanged metal or' other suitable base plate 3.

The upper end of the upper tubular prop member 1 is fitted with a flanged cap 4 which has an opening 5 for a purpose hereinafter explained. The lower end of this upper member 1 is fitted with a cylindrical body 6 having a nice sliding fit in the lower um 7 may consist of any suitable granular prop member 2 and Vtherebyfacting as a form of piston or abutment between which and the base 3 is compressed the medium 7 which resists the downward movement of the upper prop. member. 1. This medior fine particle material and can be Vfed into the lower prop member 2 by removing the Vbase 8 or through a suitable opening in the base 3 or the side of the member 2 such opening beingnormally closedA by a suitable closure member. Alternatively the Vfilling medium 7 can be delivered intorthe upper `end of the lower member 2'by removing the downwards thusavoiding su n tures and giving an indication that the roof is dangerous.

upper member 1. r

The upper member 1 is guided through a metal cap 8 detachably secured to the top of the lower prop member 2, this cap having-a collar portion8vL embracing the upper end of the member 2 and secured in position by passing locking pins 9 through openings This ysliding movement can be obtained by making the piston 6 ofannular' form and securing across vits upper faceV a thin metal or other suitable disc 10 having a fairly restricted central opening 11 through Vwhich'at excessive loads therrfilling medium 6 can be forced. It is preferred to 'havethe inner surface of the annular piston 6 conical as shown to assist in the passage of the filling medium through the opening 11, and for the same purpose the disc 10 can be composed of a number of relatively movable segments, for instance four as shown in Fig. 3, each secured tothe piston 6 by a screw 12.

Instead of forming the disc 10 of a num-Y berof segments it can be formed with a number of slits 13 (see Figs. 5 and 6) radiating from the centralopening 11, the disc being of a fairly flexible nature.

Any filling material passing into the upper prop member 1 can be removed through` the opening 5 in the cap 4.

Vhen it is desired to reduce the effective height of the prop some of the filling medium 7 can be removed from thelower ro member 2. One convenient method `o ef fecting this is to provide one or more open-k ings 14 in the lower end of the member 2, each such vopening 14 being normally closed by a movable lcover plate 15. The introduction of a suitable tool through the hole 14 will `loosen the` material in theflower prop members'and enable the desired quantity to be withdrawn through the hole.

Insteadof having one or more holes 14 inV the side of t-he member 2, a hole 15 (see Fig. 7) can beformed in 'the centre of the base plate S-so as-to curve downwards and to radiate horizontally through the base plate, its outerfend being normally closed by a screw plug 16. Theypassage of the-filling medium through this opening 15 can'be assisted by a wire 17 -of aV preferably flexible nature attachedY to the plug 16 and passing through the opening 15 into the interior of the lowery prop member 2. The removal of the plug 16,will drawthe wire 17 withit, with a consequentloosening and 'releasing of some of the filling material. The wire may be of sufficient length to occupy'a considerable proportion of the space andv thus allow adjustment according to the amount of wire withdrawn. If desired the hole may be of such a sizethat the wire will cause some'of the sand or the like to come out with it.

An adjustable pit prop constructedv according to my invention is exceedingly durable and may be used for many years'in different positions. The stone or other dust being slightly compressible affords a suitably resilient supporting material'andthe releasing means such as the conical Opening and apertured disc permits some of the material toescape kso as Ato prevent thev prop being subjected to excessiveloads thus i avoiding the risk of damage to the prop.

It is capable of being readily and quickly adjusted in length in accordance with the position in which it is required to be used and it affords a safe and effective support.

Ik claim i n i 1. A support comprising a tubular memsc Y ber closed at one end, a second tubular member slidable Within said iirst mentioned tubular member and terminating therewithin in a piston-like abutment, granular material lling the space between said abutment and the closed end of said rfirst mentioned tubular member, and an aperture near the closed end of said irst mentioned tubular member, said aperture being closed by a plug to which is attached a flexible Wire which extends Within said granular materialand is adapted when Withdrawn to remove some of said 'granular material there'- by enabling the axial length of said support to be reduced.

2. A support comprising a tubular member closed at one end, a second tubular member slidable Within said lirst tubular. member and terminating therewithin in a pistonlike abutment, granular material filling said lirst mentioned tubular member against which said abutment rests, a conical opening in said abutment having its larger end adjacent said granular material, and an apertured disc formed in segments allixed to said abutment for substantially closing the y inner end of the conical opening therein.

3. A support comprising a tubular member closed at one end and having an aperture near said end, a second tubular member slidable Within the first mentioned tubular member and terminating therewithin in a piston-like abutment, a flexible wire andl granular material filling the space between said abutment and the closed end of said .first mentioned tubular member, said Wire being Withdrawable through said aperture thereby enabling the axial length of said support to be reduced.

ENocn BULLOUGH. 

